This invention relates to an electrical switching device. More particularly, this invention relates to novel switching assembly mounted on a handpiece for actuating electrically the hand-held device. At present there exists a tremendous quantity of hand-held electrical powered devices of all sizes and uses, from low horsepower drills, powered toothbrushes, electrical shavers to rather large commercial drills, saws, etc. In many of these devices the on-off switch is located on the hand-held portion of the device, on a pistol grip or other convenient location. Generally the electrical switch, while custom designed for the specific device, is a variation of a conventional low power electrical switch employing either push button or toggle actuation to make or break contact points. Such switches are generally sufficiently safe, reliable and economical for such purposes and are so numerous and commonplace that they need not be further described herein.
I have invented a novel switch and hand-held assembly for use in a moist environment which has the advantages of convenient mode of operation, substantially longer life than conventional switches as well as reliability, esthetic appeal and safety. Basically, my invention comprises a flexible miniature membrane switch mounted internally of the outside casing of the device and responsive to axially applied actuation in the finger grip area of the handpiece. Such a switch and handpiece combination is particularly useful in dental ultrasonic prophylaxis units, which are employed by dentists for cleaning teeth. Such prophylaxis ultrasonic dental handpieces are commonly used by dentists and employ an ultrasonically vibrating tip to clean the teeth by "scaling" the surfaces thereof while simultaneously a spray or stream of water is directed in the vicinity of the operating tip by the unit. The vibrating tip is generally actuated by some form of electromechanical excitation within the handpiece. Generally the handpiece does not have an on-off switch mounted thereon because of its being subject to the moist or wet environment existing in and near the mouth of the patient. The on-off switch is generally present in the remotely located generator for the unit or if desired on a foot switch which directly controls the generator.
Examples of such ultrasonic dental prophylactic units are shown by U.S. Pat. No. 3,956,826 issued May 18, 1976 for Ultrasonic Device and Method and commonly assigned, U.S. Pat. No. 3,076,094 issued Feb. 5, 1963 for Acoustically Vibrated Material Cutting and Removing Devices and U.S. Pat. No. 3,075,288 issued Jan. 29, 1963 for Dental Instrument.
It is therefore an object of this invention to provide a novel handpiece switching device;
It is yet another object of this invention to provide a miniature, reliable electrical switch suitable for finger pressure actuation.
Still another object of the present invention is to provide a switching device which is substantially protected from a moist or wet environment.
Yet another object of the present invention is to provide a substantially waterproof, airtight switch.
Another object of the present invention is to provide a finger operated switch in a dental hand-held instrument,
Yet another object of the present invention is to provide a reliable, rugged, readily maintained handpiece switch assembly.
Still another object of the present invention is to provide a switch utilizing a minimum of space in a tubular handpiece.
Other objects and advantages of the present invention will be apparent from the summary, brief description of the drawings and the preferred embodiment which follows.